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Abstract:

Inserts are disposed in water passages of the engine of an outboard motor
in order to inhibit the flow of water, drawn from a body of water, in
thermal communication with certain portions of cylinder walls of the
engine. Extensions are formed as an integral part of the inserts in order
to maintain the proper location of the inserts within the cooling
passages.

Claims:

1. An outboard motor cooling system, comprising:an engine comprising a
block portion and a head portion, said block portion having a cylinder
disposed to support a piston therein for reciprocation along a generally
horizontal path;a water passage formed within said engine and disposed in
thermal communication with said cylinder, said water passage having a
first portion extending in a direction toward a crankcase of said engine
and a second portion extending in a direction toward said head, said
first and second portions being spaced apart horizontally;a water pump
disposed in fluid communication with said water passage and with a body
of water in which said outboard motor is operating, said water pump being
configured to draw water from said body of water and induce said water to
flow through said water passage; andan insert disposed within said water
passage at a location which inhibits said water from flowing in thermal
communication with a portion of said cylinder extending away from said
head in a horizontal direction.

2. The cooling system of claim 1, wherein:said location is within said
first portion of said water passage.

3. The cooling system of claim 1, further comprising:an extension, formed
as an integral portion of said insert and extending in a direction into
said second portion of said water passage.

4. The cooling system of claim 1, wherein:said insert is made of a water
impermeable material.

5. The cooling system of claim 1, wherein:said insert is shaped to provide
an interference fit with said water passage.

6. The cooling system of claim 1, wherein:said insert is configured to
have a plurality of ribs formed on at least one of its surfaces.

7. The cooling system of claim 1, wherein:said engine comprises two of
said cylinders, said water passage is disposed in thermal communication
with said two cylinders, said insert being disposed within said water
passage at said location which inhibits said water from flowing in
thermal communication with said portions of said two cylinders extending
away from said head.

8. The cooling system of claim 1, wherein:said water is returned to said
body of water after passing through said water passage in thermal
communication with said cylinder.

9. An outboard motor cooling system, comprising:a four stroke engine
comprising a block portion and a head portion, said block portion having
a cylinder disposed to support a piston therein for reciprocation along a
generally horizontal path;a water passage formed within said engine and
disposed in thermal communication with said cylinder, said water passage
having a first portion extending in a direction toward a crankcase of
said engine and a second portion extending in a direction toward said
head, said first and second portions being spaced apart horizontally;a
water pump disposed in fluid communication with said water passage and
with a body of water in which said outboard motor is operating, said
water pump being configured to draw water from said body of water and
induce said water to flow through said water passage; andan insert
disposed within said water passage at a location which inhibits said
water from flowing in thermal communication with a portion of said
cylinder extending away from said head, said location being within said
first portion of said water passage and spaced apart from said head in a
horizontal direction.

10. The cooling system of claim 9, wherein:said insert is shaped to
provide an interference fit with said water passage.

11. The cooling system of claim 10, further comprising:an extension,
formed as an integral portion of said insert and extending in a direction
into said second portion of said water passage.

12. The cooling system of claim 9, wherein:said engine comprises two of
said cylinders, said water passage is disposed in thermal communication
with said two cylinders, said insert being disposed within said water
passage at said location which inhibits said water from flowing in
thermal communication with said portions of said two cylinders extending
away from said head.

13. The cooling system of claim 9, wherein:said insert is made of a water
impermeable material.

14. The cooling system of claim 9, wherein:said insert is configured to
have a plurality of ribs formed on at least one of its surfaces.

15. The cooling system of claim 9, wherein:said water is returned to said
body of water after passing through said water passage in thermal
communication with said cylinder.

16. An outboard motor cooling system, comprising:an engine comprising a
block portion and a head portion, said block portion having a cylinder
disposed to support a piston therein for reciprocation along a generally
horizontal path;a water passage formed within said engine and disposed in
thermal communication with said cylinder, said water passage having a
first portion extending in a direction toward a crankcase of said engine
and a second portion extending in a direction toward said head, said
first and second portions being spaced apart horizontally;a water pump
disposed in fluid communication with said water passage and with a body
of water in which said outboard motor is operating, said water pump being
configured to draw water from said body of water and induce said water to
flow through said water passage, said water being returned to said body
of water after passing through said water passage in thermal
communication with said cylinder; andan insert disposed within said water
passage at a location which inhibits said water from flowing in thermal
communication with a portion of said cylinder extending away from said
head in a horizontal direction.

17. The cooling system of claim 16, wherein:said engine comprises two of
said cylinders, said water passage is disposed in thermal communication
with said two cylinders, said insert being disposed within said water
passage at said location which inhibits said water from flowing in
thermal communication with said portions of said two cylinders extending
away from said head.

18. The cooling system of claim 17, wherein:said location is within said
first portion of said water passage, said insert being shaped to provide
an interference fit with said water passage.

19. The cooling system of claim 18, wherein:said insert is made of a water
impermeable material and is configured to have a plurality of ribs formed
on at least one of its surfaces.

20. The cooling system of claim 19, further comprising:an extension,
formed as an integral portion of said insert and extending in a direction
into said second portion of said water passage.

Description:

BACKGROUND OF THE INVENTION

[0001]1. Field of the Invention

[0002]The present invention is generally related to cooling systems for
engines and outboard motors and, more particularly, to inserts that are
intended to affect the rate of flow of cooling water through the water
jackets formed within the structures of those engines.

[0003]2. Description of the Related Art

[0004]Those skilled in the art of marine propulsion systems are aware of
many different cooling systems used to control the operating temperature
of engines used in those marine propulsion devices. Marine propulsion
devices present a specific and unique difficulty in the control of engine
operating temperatures. Open systems, in which water is drawn from a body
of water and pumped through cooling passages of the engine, are forced to
use the water drawn from those bodies of water as the cooling medium.
That water can vary significantly in temperature from nearly freezing to
temperatures in excess of 80 degrees Fahrenheit. Although thermostats can
be used to affect the rate of flow of cooling water through engine water
passages, the initial intake of cooling water from a body of water can
significantly reduce the temperature of certain portions of the engine to
magnitudes that can lead to significant fuel dilution problems. As an
example, overcooled cylinder walls can condense fuel vapors to liquid
form and cause the condensed fuel to mix with oil used for lubrication.
That mixing of condensed fuel with lubricating oil, which is referred to
herein as dilution, can adversely affect the operation of the engine if
it is not appropriately addressed. The problem of very cold water being
drawn directly from a body of water and pumped to the cooling passages of
an engine are not experienced in land vehicles which incorporate closed
cooling systems that can more easily be regulated to control the internal
operating temperature of both the coolant and the engine through which
the coolant flows.

[0005]British patent 1,012,082, which was published on Dec. 8, 1965,
describes a cooling system for an internal combustion engine. An internal
combustion engine has a cylinder wall comprising a cast portion in which
a liner is located, a cooling passage adjacent to the outer surface of
the cylinder wall, a piston which is reciprocable within the cylinder
adjacent the inner surface of the cylinder wall, a cylinder head closing
one end of the cylinder, and a liner that has projections on its outer
surface which contact the inner surface of the cast portion of the wall
of the cylinder and the projections are dimensioned, shaped and
positioned to give a greater degree of heat transfer to the cast portion
of the cylinder wall at the combustion end of the cylinder than at the
other end for a given temperature difference between the inner and outer
surfaces of the wall.

[0006]U.S. Pat. No. 4,569,313, which issued to Nobu on Feb. 11, 1986,
describes a cooling water path for an internal combustion engine. The
path is characterized in that within a water jacket in the cylinder head
there are installed a plurality of head partition walls located between
adjacent cylinders extending the full width of the head with a
ventilation hole provided at the top.

[0007]U.S. Pat. No. 6,295,954, which issued to Suzuki on Oct. 2, 2001,
describes a cylinder block for water cooled engines. The engine has a top
deck, a cylinder wall structure defining a row of cylinder bores, and a
water jacket wall structure defining a water jacket around the cylinder
bores. The jacket wall structure has a plurality of cylinder head bolt
bosses each formed with a bolt hole for a cylinder head bolt for
fastening a cylinder head at the top deck of the cylinder block.

[0008]U.S. Pat. No. 6,834,625, which issued to Matsutani et al. on Dec.
28, 2004, describes a cooling apparatus of an internal combustion engine.
A cooling apparatus of an internal combustion engine includes a closed
deck type cylinder block and an insert. The cylinder block includes a
water jacket and an upward deck including a water hole formed therein.
The insert is disposed in the water jacket and inserted into the water
jacket through the water hole. The insert is fixed relative to the
cylinder block at a water hole portion such that the insert is fixed in
position in a flow direction of the cooling water.

[0009]U.S. Pat. No. 6,874,451, which issued to Matsutani et al. Apr. 5,
2005, describes a cooling apparatus of an internal combustion engine. It
includes an insert that is deformable, and a surface of the insert
opposing a cylinder bore wall is close to the cylinder bore wall after
the insert is inserted into a water jacket. A cooling apparatus of an
internal combustion engine includes a cylinder block having a water
jacket in which an insert is disposed. The cylinder block is machined so
that a water hole or an aperture having a size corresponding to a size of
the insert is formed in the cylinder block and the insert can be inserted
into the water jacket through the water hole the aperture.

[0010]U.S. Pat. No. 7,032,547, which issued to Xin on Apr. 25, 2006,
describes a cylinder block cooling arrangement for a multi-cylinder
internal combustion engine. An insert of a Siamese-type internal
combustion engine that separates a water jacket surrounding the cylinders
into an upper portion and a lower portion is described. Below a
predetermined engine speed coolant flows primarily in the upper water
jacket portion so as to provide enhanced cooling at the upper portions of
the cylinders. Above a predetermined engine speed coolant is introduced
into the lower water jacket portion from the upper water jacket portion
so as to provide improved cooling of the lower cylinder portions, without
compromising cooling of the upper cylinder portions or the conjoined
cylinder wall portions.

[0011]The patents described above are hereby expressly incorporated by
reference in the description of the present invention.

[0012]An article, titled "Fuel Savings for Toyota" describes the use of
inserts within cooling jackets of internal combustion engines for
automobiles. The inserts are described as resulting in a significant fuel
economy saving of approximately 1%. The function of the water jacket
spacer is the equalization of the cylinder wall temperatures and average
engine temperatures. The water jacket spacer addresses this challenge by
reducing the friction between pistons and cylinders. The upper part of
the spacer adjusts and cools down the flow rate of the coolant. The lower
part limits the flow rate of the coolant and keeps it relatively warm.

[0013]Inserts, disposed within cooling jackets of engines, are generally
known to those skilled in the art for use in internal combustion engines
that are used in land vehicles with closed cooling systems. These
vehicles use closed cooling systems in which the coolant is recirculated
continually under the operational control of one or more thermostats. As
such, the temperature of the coolant can be controlled with relatively
high accuracy to prevent overcooling or overheating of portions of the
engine relative to other portions. Internal combustion engines used in
marine propulsion devices often incorporate open cooling systems in which
water is drawn from a body of water in which the marine propulsion device
is operated. No control is available over the incoming temperature of the
water drawn from the lake or ocean and pumped directly to the cooling
passages of the engine. This presents a unique difficultly since very
cold cooling water can overcool certain portions of the engine.
Meanwhile, other portions of the engine, which are heat producing,
require the temperature to be maintained below certain upper threshold
magnitudes.

[0014]It would therefore be significantly beneficial if a cooling system
could be provided in which cooling water is allowed to flow easily to
certain heat producing regions of the engine while being inhibited from
flowing directly into other non-heat producing portions.

SUMMARY OF THE INVENTION

[0015]An outboard motor cooling system, in accordance with a preferred
embodiment of the present invention, comprises an engine which comprises
a block portion and a head portion. The block portion has a cylinder
disposed to support a piston therein for reciprocation along a generally
horizontal path. A water passage is formed within the engine and disposed
in thermal communication with the cylinder. The water passage has a first
portion extending in a direction generally toward a crankcase of the
engine and a second portion extending in a direction generally toward the
head of the engine. A water pump is disposed in fluid communication with
the water passage and with a body of water in which the outboard motor is
operating. The water pump is configured to draw water from the body of
water and induce the water to flow through the water passage. An insert
is disposed within the water passage at a location which inhibits the
water from flowing in thermal communication with a portion of the
cylinder extending away from the head.

[0016]In a preferred embodiment of the present invention, the location in
which the insert is disposed within the water passage is within the first
portion of the water passage. In certain embodiments, the present
invention can further comprise an extension formed as an integral portion
of the insert and extending in a direction into the second portion of the
water passage. The insert is made of a water impermeable material in a
preferred embodiment of the present invention and is shaped to provide an
interference fit with the water passage. The insert is configured to have
a plurality of ribs formed on at least one of its surfaces in a preferred
embodiment. The engine can comprise two cylinders. The water passage can
be disposed in thermal communication with both of the two cylinders. The
insert can be disposed within the water passage at the location which
inhibits the water from flowing in thermal communication with the
portions of the two cylinders extending away from the head. The water is
returned to the body of water after passing through the water passage in
thermal communication with the cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]The present invention will be more fully and completely understood
from a reading of the description of the preferred embodiment in
conjunction with the drawings, in which:

[0018]FIG. 1 shows the engine block of an engine of a 4-stroke outboard
motor;

[0019]FIG. 2 is a side section view of the engine in FIG. 1;

[0020]FIG. 3 is a highly schematic representation showing the flow of
water from a body of water into the engine cooling passages of an
outboard motor;

[0021]FIGS. 4 and 5 show isometric views of two inserts used in a
preferred embodiment of the present invention;

[0022]FIG. 6 is a graphical representation of surface temperatures taken
during empirical studies of a preferred embodiment of the present
invention;

[0023]FIG. 7 shows a series of oil temperatures taken at various engine
speeds; and

[0024]FIG. 8 shows the beneficial effects on percent oil dilution
resulting from the use of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0025]Throughout the description of the preferred embodiment of the
present invention, like components will be identified by like reference
numerals.

[0026]FIG. 1 shows an engine 10 having two cylinders, 21 and 22. In FIG.
1, two inserts, 31 and 32, are shown disposed within a water jacket
surrounding the cylinders, 21 and 22.

[0027]FIG. 2 is a side section view of the illustration shown in FIG. 1.
For purposes of reference, point 40 is an axis of rotation of a
crankshaft (not shown in FIGS. 1 and 2) that is connected by connecting
rods to pistons disposed in the first and second cylinders, 21 and 22.
The pistons are not shown in FIGS. 1 and 2. The inserts, 31 and 32, are
disposed within a cooling jacket 44 that surrounds the cylinders. The
upper surface 50 of the engine block is shaped to receive a gasket on its
planar surface and a head portion of the engine, with the gasket being
disposed between the engine block 60 and the engine head (not shown in
FIGS. 1 and 2). Those skilled in the art of engine construction are well
aware of the various types of engine heads that can be used to form an
engine with the engine block shown in FIGS. 1 and 2.

[0028]FIG. 3 is a highly schematic representation of an outboard motor
showing the engine block 60 and an engine head 61 attached to the block.
It should be understood that, although FIG. 3 shows the head 61 above the
block 60, this is not the case in the normal arrangement of the engine of
an outboard motor. Instead, the head portion 61 is disposed at a forward
position in front of the block portion 60. In other words, the pistons
within the cylinders move in a reciprocating pattern along horizontal
axes. The crankshaft is supported for rotation about a generally vertical
axis and it drives a driveshaft that extends vertically downward through
a driveshaft housing. The driveshaft is connected in torque transmitting
relation with the propeller shaft which causes a rotation of a propeller.
Water is drawn by a pump 70 and caused to flow in the direction of the
arrows in FIG. 3 to the engine block 60. The water flows through various
cooling passages and cooling jackets within the engine block 60 and the
head 61. The arrows in FIG. 3 show the water passage as extending upward
only through the engine block 60 from which it returns to the body of
water 68 from which it was drawn. This is an open loop cooling system, in
which water from the body of water 68 is used to remove heat from heat
generating portions of the engine and then return to the body of water.
The water flows through the engine at approximately the temperature of
the water within the body of water 68. Although some slight warming
occurs as it passes through the engine, the water is initially at the
temperature of the body of water when it is drawn upwardly by the pump
70.

[0029]With continued reference to FIGS. 1-3, points 81 and 82 in FIG. 1
represent axes along which pistons are supported within the cylinders 21
and 22 for reciprocal motion. It should be understood that the primary
heat producing region in FIG. 2 is the upper portion of the cylinders
closest to the combustion chambers within the head. It can be seen that
the inserts, 31 and 32, fill a majority of the cooling jacket 44 in the
portion which is farther from the engine head and closest to the
crankcase 88. The walls of the cylinders closest to the crankcase 88
receive the least amount of heat generated during the combustion process.

[0030]FIGS. 4 and 5 are isometric views of the inserts, 31 and 32,
described above in conjunction with FIGS. 1 and 2. When the cooling
jackets 44 are formed during a casting procedure, the depth is not
necessarily uniform for all portions of the cooling jacket. This is due
to various limitations required to provide a satisfactory casting. In
addition, the depth of the water jacket, measured as a distance from
surface 50, is sometimes greater than is necessary for cooling purposes.
Therefore, the cylinders, 21 and 22, can be overcooled if the entire
cooling jacket 44 is used. With the inserts, 31 and 32, disposed within
the cooling jacket 44, water drawn from the body of water 68, as
described above in conjunction with FIG. 3, is prevented from circulating
in the portion of the cylinder wall most proximate the crankcase 88 and
farthest away from the heat generating region of the combustion chamber.

[0031]With continued reference to FIGS. 4 and 5, it can be seen that the
height of insert 31 is significantly less than the height of insert 32
because of the configuration of the water jacket 44 illustrated in FIG.
2. It can also be seen that both inserts, 31 and 32, have ribs 90
extending along the surface 92 that faces inwardly toward the cylinders,
21 and 22, as described above in conjunction with FIGS. 1 and 2.

[0032]With continued reference to FIGS. 1-5, it can be seen that the
primary purpose of the inserts, 31 and 32, is to fill a portion of the
water jacket 44 and prevent the circulation of cold water proximate the
walls of the cylinders that are in a region farthest from the heat
producing portions near the combustion chambers. In other words, they
take up space that would otherwise be filled with cold water that could
be drawn from the body of water 68 in the manner described above.

[0033]One of the primary problems in engine cooling systems associated
with marine propulsion devices is that very cold water can be drawn from
a body of water 68 and caused to flow in thermal communication with
various portions of the cooling passages of the engine. If portions of
the cylinders walls are overcooled, this can lead to the condensation of
fuel from the fuel vapor circulating within the cylinders. If this
condensation occurs, the pistons can wipe the condensed fuel droplets in
a direction toward the crankcase and cause the condensed fuel to mix with
the oil within the crankcase. This creates a dilution of the oil and can
have a deleterious effect on its lubricating capabilities. Eventually, it
can collect in the oil sump to the degree that actually causes the oil
sump to overflow because of the additional quantity of liquid provided by
the condensed fuel. Both situations can be seriously disadvantageous to
the proper operation of a marine engine. One of the primary functions of
the present invention is to prevent or inhibit the overcooling of the
portion of the cylinders walls farthest from the combustion chambers in
the head of the engine and closest to the crankcase.

[0034]FIG. 6 is a graphical representation of some test results performed
during the development of the present invention. It shows a line 100 that
represents the average engine cylinder wall temperatures taken at various
selected locations in an engine incorporating the inserts, 31 and 32, of
the present invention. Line 110 represents the same engine without the
inserts in place. As can be seen, the temperatures are significantly
higher at the selected engine wall locations in the engine 100 that
includes the inserts. By raising the engine wall temperatures,
condensation of fuel vapor is decreased and, as a result, the amount of
dilution of the engine oil is significantly decreased. FIG. 7 is a
graphical representation which shows a line 200 that represents oil
temperature at various engine speeds of the oil sump temperatures in an
engine incorporating the inserts, 31 and 32, of the present invention.
Line 210 shows the oil sump temperatures in an engine which does not
contain the inserts. The consistent increase at all engine operating
temperatures can be seen.

[0035]With continued reference to FIGS. 6 and 7, it should be understood
that the surface temperatures represented in FIG. 6 and the oil
temperatures represented in FIG. 7, by themselves, do not represent a
functional improvement that is the primary goal of the present invention.
Instead, the temperatures of the surfaces illustrated in FIG. 6 and the
oil illustrated in FIG. 7 show an intermediate result that leads to the
intended beneficial result which will be described below.

[0036]FIG. 8 shows actual measurements of percent oil dilution, by volume,
taken during the operation of two engines. Line 300 shows the actual
measured oil dilution percentage for a 20 horsepower 4-stroke engine that
does not include the inserts of the present invention. Line 310 shows the
actual measured oil dilution percentages, by volume, resulting in a 20
horsepower 4-stroke engine that includes the inserts of the present
invention. During the testing that resulted in the data shown in FIG. 8,
the engines were run at a constant 4300 RPM for two hours. After a
preliminary warm-up period, the percentage of oil dilution was measured
at zero minutes after the warm-up, 30 minutes, 60 minutes, 90 minutes,
and 120 minutes after the warm-up. As is dramatically evident in FIG. 8,
the percentage of oil dilution represented by line 300 is significantly
higher than that represented by line 310. Line 310 shows the results and
the improvement obtained through the use of the inserts of the present
invention. By reducing the amount of cooling water flowing through the
regions of the water jacket 44 closest to the crankcase and furthest from
the combustion chambers, the percentage of oil dilution is significantly
reduced.

[0037]With continued reference to FIGS. 1-8, it can be seen that an
outboard motor cooling system made in accordance with a preferred
embodiment of the present invention comprises an engine having a block
portion 60 and a head portion 61. The block portion 60 has a cylinder, 21
or 22, disposed to support a piston therein for reciprocation along a
generally horizontal path, 81 or 82. A water jacket 44 formed within the
engine and disposed in thermal communication with the cylinder, 21 or 22,
is disposed within the engine block. The water jacket 44 has a first
portion extending in a direction toward a crankcase 88 of the engine and
a second portion extending in a direction toward the head. A water pump
70 is disposed in fluid communication with the water jacket 44 and with a
body of water 68 in which the outboard motor is operating. The water pump
70 is configured to draw water from the body of water 68 and induce the
water to flow through the water jacket 44. An insert, 31 or 32, is
disposed within the water jacket 44 at a location which inhibits the
water from flowing in thermal communication with a portion of the
cylinder extending away from the head 61.

[0038]With continued reference to FIGS. 1-8, the location in which the
insert is disposed is within the first portion of the water jacket 44.
This is shown in FIG. 2. An extension 35 is formed as an integral portion
of the insert, 31 or 32, and extends in a direction into the second
portion of the water passage. In other words, the extensions extend from
the main body of the inserts, 31 and 32, and toward the head 61 and away
from the crankcase 88. The primary purpose of the extensions 35 is to
maintain the location of the main body of the inserts at their locations
which are closest to the crankcase 88 and away from the head 61. In a
preferred embodiment of the present invention, the inserts, 31 and 32,
are made of a water impermeable material. Such a material is
thermoplastic copolyester elastomer which is available in commercial
quantities from the DuPont Corporation under the name Hytrel 5526. The
inserts, 31 and 32, are shaped to provide an interference fit with the
water jacket 44. The insert is configured to have a plurality of ribs 90
formed on at least one of its surfaces. The engine, in one embodiment of
the present invention, comprises two cylinders, 21 and 22. The water
jacket 44 is disposed in thermal communication with the two cylinders, 21
and 22, and the insert is disposed within the water passage at the
location which inhibits the water from flowing in thermal communication
with the portions of the two cylinders extending away from the head 61.
The water is returned to the body of water 68 after passing through the
water jacket 44 in thermal communication with the cylinder.

[0039]Although the present invention has been described with particular
specificity and illustrated to show a preferred embodiment, it should be
understood that alternative embodiments are also within its scope.

Patent applications in class With liquid coolant circulating means

Patent applications in all subclasses With liquid coolant circulating means